[PATCH v2] [gdb/symtab] Fix dwarf version of DWO TU

[Tom de Vries <tdevries@suse.de>]

When running test-case gdb.ada/access_tagged_param.exp with target board
fission, we run into:
...
(gdb) break pck.adb:19^M
gdb/dwarf2/read.h:289: internal-error: version: \
  Assertion `m_dwarf_version != 0' failed.^M
...

The assertion happens when calling cu->per_cu->version () in this workaround
in read_subroutine_type:
...
  /* PR gas/29517 occurs in 2.39, and is fixed in 2.40, but it's only fixed
     for dwarf version >= 3 which supports DW_TAG_unspecified_type.  */
  if (type->code () == TYPE_CODE_VOID
      && !type->is_stub ()
      && die->child == nullptr
      && (cu->per_cu->version () == 2
	  || producer_is_gas_2_39 (cu)))
    {
...
for a TU in a dwo file.

Fix this by using cu->header.version instead.

Tested on aarch64-linux.

PR symtab/32309
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32309
---
 gdb/dwarf2/read.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 4503977d62b..824604261f5 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -14019,7 +14019,7 @@ read_subroutine_type (struct die_info *die, struct dwarf2_cu *cu)
   if (type->code () == TYPE_CODE_VOID
       && !type->is_stub ()
       && die->child == nullptr
-      && (cu->per_cu->version () == 2
+      && (cu->header.version == 2
 	  || producer_is_gas_2_39 (cu)))
     {
       /* Work around PR gas/29517, pretend we have an DW_TAG_unspecified_type

base-commit: c99345db064e1bd645bc08db65174bae7ac20b0e
-- 
2.43.0